With a trend toward downsizing, slimming down and digitalization of electronic apparatuses, there has been a growing demand for increase in capacitances, decrease in equivalent series resistances (“ESR”) and decrease in thicknesses of solid electrolytic capacitors for use in such electronic apparatuses.
FIG. 8 is a perspective see-through view of a conventional solid electrolytic capacitor. This solid electrolytic capacitor has capacitor element (hereinafter referred to as “element”) 51, negative terminal 52, positive terminal 53, and resin package 54. Negative terminal 52 is connected to a negative electrode portion of element 51, and positive terminal 53 is connected to a positive electrode portion of element 51. Resin package 54 covers element 51 and parts of negative terminal 52 and positive terminal 53. Certain parts of negative terminal 52 and positive terminal 53 are exposed on side faces of resin package 54, and bent along an underside from these side faces.
In element 51, a conductive polymer having an excellent electrical conductivity is used for a solid electrolyte layer. The ESR of element 51 thus is small. In addition, a surface where a dielectric oxide film is formed is etched. Element 51 has a large capacitance as a result of increasing the surface area.
Positive terminal 53 is welded to the positive electrode portion of element 51. On the other hand, negative terminal 52 is bent into a shape of letter L to form mount portion 55 inside resin package 54. Mount portion 55 is joined to an underside of the negative electrode portion of element 51 via a conductive bonding portion (not shown) formed of an electrically conductive paste. Negative terminal 52 is also provided with holder portions 56. Each of holder portion 56 is fitted into one of recesses each formed in a side face near one end of the negative electrode of element 51, and joined to the side face of the negative electrode portion via conductive bonding portion 57. The ESR of the solid electrolytic capacitor is small by virtue of these structures (Patent Literature 1, for example).